This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-121327, filed Apr. 21, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to an information storage medium that records reproducible information and, more particularly, to an improvement in recording format of the information storage medium. The present invention also relates to an information recording method and apparatus for recording a predetermined recording format on an information storage medium. Furthermore, the present invention relates to an information reproduction method and apparatus for reproducing the predetermined recording format recorded on the information storage medium.
xe2x80x9cReference dataxe2x80x9d used in the circuit adjustment of an information reproduction apparatus or in the evaluation of an information storage medium that records information can be allocated in only lead-in/lead-out areas present at the innermost and outermost peripheries of a disk in a conventional DVD (Digital Versatile Disk). In addition, the reference data is allocated at only one location in, e.g., a lead-in area at the innermost periphery.
On the other hand, before an information recording/reproduction apparatus records information on an information storage medium, it makes test write on a test write area on the information storage medium while changing recording conditions (recording power, recording pulse width, and the like), and detects the state of a signal reproduced from that area so as to check recording conditions optimal to the information storage medium. The test write area is also allocated at only one location in, e.g., a lead-in area at the innermost periphery of a disk in case of a conventional DVD-RAM disk or DVD-RW disk.
When the circuit adjustment of an information reproduction apparatus or characteristic evaluation of an information storage medium is done using the reference data present at only the innermost periphery, if a master disk used to form an information storage media suffers nonuniformity of applied photoresist or a master disk exposure apparatus suffers exposure nonuniformity, the circuit constants unmatch at the middle or outer peripheral portion of the information storage medium, and the reproduction signal becomes unstable.
When optimal recording conditions in an information recording/reproduction apparatus are set using a test write area present at only the innermost periphery, if an information storage medium suffers radial recording sensitivity nonuniformity under the influence of small thickness nonuniformity of a recording film on the information storage medium, it becomes impossible to record optimal recording conditions on an outer peripheral portion of the information storage medium.
It is an object of the present invention to provide the following information storage medium, information recording method, information recording apparatus, information reproduction method, and information reproduction apparatus that can solve the aforementioned problems:
(1) an information storage medium which records reference data to be suited to circuit constant adjustment of an information reproduction apparatus and characteristic evaluation of an information storage medium;
(2) an information recording method and apparatus for recording reference data on an information storage medium to be suited to circuit constant adjustment of an information reproduction apparatus and characteristic evaluation of an information storage medium; and
(3) an information reproduction method and apparatus capable of satisfactory reproduction of user data without being influenced by reference data upon reproducing an information storage medium that records reference data to be suited to circuit constant adjustment of an information reproduction apparatus and characteristic evaluation of an information storage medium.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.